How plants evolved to make ants their servants

When a person is unable to react to stimuli and does not show any obvious sign of self-awareness or of the environment, it is said that he has remained in a vegetative state. It is a very visual analogy with our idea of the life of plants: they seem to perform only basic life functions to stay alive, but their existence has no other grace.

But nature is more surprising than what the human eye allows us to observe. An example is the interactions between the plant world and the ants. Plants have developed specific characteristics to attract these insects as providing them with a juicy nectar or shelter in their cavities. In return, they use ants to propagate their seeds or use them for bodyguards.

A new study published in PNAS analyzes the genetic history of 1,700 ant species and 10,000 plant genera and has discovered that the long history of ants and co-evolution of plants began with ants that feed on plants and plants. Later responding by evolving friendly features with ants.

A plant that evolved hollow thorns for ants to shelter in. In exchange, the ants defend the plant from attacks from other insects and mammals.Credit: (c) Field Museum, Corrie Moreau

Some plants have developed characteristics that persuade ants to defend them from the attack of other insects and even mammals. These include hollow thorns in which the ants will live inside or additional nectar in the leaves or stems for the ants to eat, “and for Matt Nelsen, postdoctoral researcher at the Field Museum and lead author of the study,” some ants cheat and then to take the nectar they flee, but others will stay and attack anyone who tries to harm the plant. “

Rich food and shelter

Other plants use the ants to move their seeds, bribing them with rich foods attached to seeds called elaiosomes. “The ant will pick up the seed and take it away, eat the food package and discard the seed, often in a nutrient-rich area where it will grow better.”

But when did the ants start using the plants and when did they start making the structures for the ants to use? The history of ants and plants that evolve together dates back to the time of the dinosaurs, and it is not easy to distinguish from fossils how organisms interact. To determine the early evolutionary history of ant interactions, Nelsen and his colleagues turned to large amounts of DNA data and ecological databases.

The team drew a map of the history of these friendly features with the ants and thus, they were able to determine at what point the plants began to depend on the ants for the defense and distribution of seeds. Apparently, and it seems that the plants began to depend on the ants for the defense and distribution of seeds before they relied directly on the ants since the plants did not evolve these specialized structures until long after the ants found in the food and lodging.

The funny thing is that, although there has been a mutually beneficial relationship between ants and plants over the years, from an evolutionary point of view, the groups of ants that use the plants do not seem to be better than the rest. “This study is important because it provides insight into how these generalized and complex interactions evolved,” they conclude.